Outside Hose Allowance - Add Flow at System Demand Point or Add Flow at Source Node?

[Haldorson]

It seems AHJ's in my area have differing opinions on where the outside hose allowance should be added: at the system demand point or the node correlating to the nearest hydrant.

In NFPA 13 it says to add the outside hose allowance at the nearest hydrant. In Robert Gagnon's book Fire Protection Systems he shows the outside hose allowance simply being added to the system demand as a horizontal line.

Both of these methods produce different results in terms of system demand with hose allowance. Which one is correct?

 

[TravisMack]

If the hydrant is between my riser and city supply main, then I include it where it is located. If the hydrant is directly on the city main, then I just add it to my source point. So, it depends on the configuration to where the hydrant is located.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[Haldorson]

Makes sense. Thanks Travis, much appreciated.